Rubbing aprons



L. CHIOVATO ET AL Dec. 31, 1957 RUBBING APRONS Filed July 6, 1955 INVENT 0R5 United States Patent 2,817,879 RUBBING APRONS Luigi Chiovatoand Gianfranco Leguani, Milan, Italy, assignors to Pirelli, Societa perAzioni, Milan, Italy Application July 6, 1955, Serial No. 520,311 Claimspriority, application Italy July 16, 1954 3 Claims. (Cl. 19-153) Thisinvention relates to rubbing aprons for carding machines, and, moreparticularly, to such aprons having rubber outer layers provided withslits therein to improve their condensing action.

A rubbing apron is used to condense a card web prior to a spinningoperation and therefore receives a series of parallel rovings from thecard, and, by relative trans verse motion between a pair of such apronshaving the rovings passing in frictional engagement between theiradjacent surfaces, condenses the formerly loose, relatively wide,rovings, to compact, narrow rovings.

In order to improve the efiiciency of the condensing action of such anapron, it has been proposed to provide each cooperating apron withgrooves cut inward from its outer surface and extending generally in thedirection of movement of the rovings. These grooves extend spirallyaround the body of the apron and have been cut therein by removal ofmaterial, usually leather, from the body of the apron. Such grooves areusually about 3 to 5 mm. spaced, about 1.8 mm. deep, and about 1.5 mm.wide. The grooves in the aprons operate on the rovings passing by them,which are usually spaced from 40 to 50 mm. apart, to prevent theindividual rovings from being coupled together during the condensingoperation.

In use of aprons provided with grooves as above described, however, ithas been found that after a period of use, the apron surface wears downto smooth off the grooves and decrease the frictional adhesion betweenthe rovings and the apron. This results in a decrease in the efficiencyof the rubbing operation of the rubber, thus resulting in increasingfailure to form round, uniform rovings.

By the use of our invention, however, it has been found that the rubbingefficiency of the apron may be maintained constant over a very longperiod of time.

Our invention comprises a rubbing apron constructed with a rubber outersurface, and, rather than having grooves formed by removal of materialfrom the card rubber, having scores or slits cut into the rubber surfaceand extending very deeply therein.

The invention will now be more fully described in conjunction with theaccompanying drawing, in which:

Fig. 1 is a perspective view of a rubbing apron, constructed inaccordance with the invention;

Fig. 2 is a plan view of the device of Fig. 1; and

Fig. 3 is a partial sectional view, taken along line 3-3 of Fig. 2.

In the drawing, a rubbing apron is indicated generally at A. This apronis of conventional form and is adapted to operate in conjunction with anoppositely disposed similar apron, on a pair of rollers (not shown)which are conventionally rotated and reciprocated in an axial direction,to give the rovings of the web passing between the adjacent parallelsurfaces of the two aprons a rubbing action. Since apparatus which willcooperate with apron A to perform this purpose is conventional and wellknown to those skilled in this art, such apparatus is not here shown ordescribed.

This invention relates to a peculiar and novel construction of the bodyof the apron, and will now be described in conjunction with Fig. 3.

As shown in Fig. 3, the apron A consists of a base layer of rubber, twolayers of rubberized fabric 2 superimposed and fixed on the base layer,and of a rubber covering 3 fixed to the outer side of the outer fabriclayer. This particular combination of layers forming the apron isdesigned for long wear and precise operation, but it is not particularlyimportant to this invention. What is important is that the outer layer 3of the apron be of rubber, and that it have the novel characteristicsnow to be described.

In order to provide for an efficient rubbing action in operation of theapron, a number of slits 3a are cut into the surface of the outer rubberlayer of the apron substantially perpendicularly to its outer surface,these slits extending through the major portion of the depth of thelayer. The slits are preferably continuous around the surface of theapron in such form as to form a continuous helical groove therein.

The slits 3a are preferably spaced apart a distance of between 0.5 and 2mm. and each have a depth of up to W of the depth of the rubber layer 3.The slits thereby divide the outer rubber layer of the apron into amultiplicity of relatively thin rubber plates 4, attached to the base ofthe outer rubber layer only at their inner sides.

During the rubbing action of the apron, the rubber plates 4 of the apronbend like the hair of a brush, as shown at 5 in Fig. 3.

Tests of aprons constructed as detailed above have shown that aconstant, high level, rubbing action is obtained therewith, and that thelife of the apron is quite long, terminating only when the rubber plates4 have worn down to the uncut portion of rubber layer 3.

It is, of course, not essential that the slits 3a in the outer rubberlayer be continuous to form a helical groove, but rather this inventionincludes any arrangement of such slits as long as they penetrate themajor portion of the depth of the outer rubber layer, up to W of saiddepth, and as long as the slits are made without removal of materialfrom the apron and are spaced close together, preferably between 0.5 and2 mm. apart. It will be understood that the term slit, as used in thisdescription and the appended claims, refers to knife-cuts in the surfaceof the rubber layer, and does not cover grooves in the surface formed byremoval of material therefrom.

We claim:

1. A rubbing apron for a card condenser having an outer layer of rubberextending over its operative surface and adapted to be reciprocatedsubstantially perpendicularly to the direction of travel of the web withwhich the apron is to be used, said rubber layer having a multiplicityof slits therein extending generally in the direction of travel of theweb and around the periphery of the apron, said slits extendingsubstantially perpendicularly to the outer surface of the rubber layerthrough the major portion of the depth thereof, and said slits beingspaced closely to define a multiplicity of narrow rubber blocks in thesurface of the apron which bend oppositely to the direction of travel ofthe apron during its reciprocating motion to assist the condensingaction.

2. The apparatus defined in claim 1 in which said slit are spaced apartbetween 0.5 and 2 min. and extend through up to of the depth of therubber layer.

3. The apparatus of claim 2 in which said slits form a continuoussubstantially helical path around the surface of the rubber layer.

References Cited in the file of this patent UNITED STATES PATENTS489,281 Barker Jan. 3, 1893 1,442,767 Hunter et al. Jan. 16, 19232,434,820 Tifi't Jan. 20, 1948

